Response to selection for reduced grain saponin content in quinoa (Chenopodium quinoa Willd.)

A major impediment to expanding production of the traditional pseudocereal quinoa outside its Andean center of origin is the high level of grain saponin in early-maturing daylength-neutral lines which can be grown at higher latitudes. Screening of South American quinoa accessions in Colorado revealed significant among-plant within-cultivar variation for grain saponin content in some lines; heritability for the trait was estimated at 0.37 based on parent-offspring regression. Three cycles of pedigree selection did not reduce population means or identify any family which was consistently low saponin, although among pooled progeny the proportion of plants with less than 1 mg g(-1) grain saponin increased from 3.57% in the S-1 to 11.1% in the S-4. Skewed progeny distribution frequencies, continued segregation for grain saponin content, and the persistence of high-saponin individuals in all generations indicated that dominance effects are a major component of genetic variance for the trait. Due to the allotetraploid nature of quinoa, fixed heterozygosity at loci controlling saponin content may also occur. Given the limited response to selection, quinoa breeders may wish to use alternative methods for reducing grain saponin levels in the crop. (C) 2000 Elsevier Science B.V. All rights reserved.